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      Effect of bipolar pulsed radiofrequency on refractory chronic cervical radicular pain : A report of two cases


      , MD


      Wolters Kluwer Health

      bipolar, cervical radicular pain, chronic pain, pulsed radiofrequency, refractory pain

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          Despite undergoing transforaminal epidural steroid injection (TFESI), many patients complain of persisting cervical radicular pain. For the management of chronic cervical radicular pain, clinicians are widely applying pulsed radiofrequency (PRF) stimulation to dorsal root ganglions (DRGs). To enhance the effect of PRF stimulation, we conducted bipolar PRF stimulation in 2 patients with chronic cervical radicular pain that was refractory to monopolar PRF and repeated TFESIs.

          Patient concerns:

          Patients 1 and 2 presented with a numeric rating scale (NRS) score of 7 and 6 for chronic cervical radicular pain, respectively, despite undergoing monopolar PRF and 2 TFESIs.


          On cervical magnetic resonance imaging, foraminal stenosis at the right C6–7 and right central to right foraminal disc protrusion on C6–7 were observed in patients 1 and 2, respectively. Two patients showed a positive response on diagnostic right C7 selective nerve root block with 0.5 mL of 1% lidocaine.


          Bipolar PRF stimulation was performed under C-arm fluoroscopy. Two parallel RF cannulas (less than 1 cm apart) were used for DRG stimulation. The PRF treatment was administered at 5 Hz and a 5-ms pulsed width for 360 seconds at 45 V with the constraint that the electrode tip temperature did not exceed 42°C.


          At the 2-week and 1-month follow-up, after undergoing bipolar PRF, the pain of patient 1 was completely relieved, and at 2, 3, and 6 months, the pain was scored as NRS 2. In patient 2, at the 2-week follow-up after undergoing bipolar PRF, pain severity was reduced from NRS 6 to 2. The effect of bipolar PRF on patient 2 lasted for at least 6 months. No adverse effects were observed in either patient.


          Application of bipolar PRF to DRGs seems to be an effective and safe technique for treating refractory chronic cervical radicular pain.

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          Most cited references 28

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          Electric and thermal field effects in tissue around radiofrequency electrodes.

           Eric Cosman (2015)
          A study is carried out of the spatial distribution and time dependence of electric and thermal fields in the tissue around a radiofrequency (RF) electrode used in pain therapy. Finite-element calculation of the fields is performed, and results are compared with ex vivo tissue data. Field predictions are made for continuous and for pulsed RF applications. A special RF cannula electrode is constructed with both macro and micro thermocouple sensors to measure both average and rapid, transitory temperature effects. Temperatures and impedances are recorded in liver and egg-white models using signal outputs from a commercially available RF lesion generator. These data are compared with the results of finite-element calculations using electric field equations and the bio-heat equation. Average and pulsatory temperatures at the RF electrode are measured. Rapid temperature spikes during pulsed RF bursts are observed. These data compared well with theoretical calculations using known electrical and thermal tissue parameters. Continuous RF lesioning causes heat destruction of neurons. Pulsed RF lesioning (PRFL) produces heat bursts with temperatures in the range associated with destructive heat lesions. PRFL also produces very high electric fields that may be capable of disrupting neuronal membranes and function. Finite-element calculations agree substantially with the measured data, giving confidence to their predictions of fields around the RF electrode.
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            Ultrastructural changes in axons following exposure to pulsed radiofrequency fields.

            Pulsed radiofrequency (PRF) fields applied by an electrode to neural structures, such as the peripheral sensory nociceptor axons and dorsal root ganglion, are clinically effective in reducing pain and other neuropathic syndromes. However, a full understanding of the underlying mechanisms by which this occurs has not yet been clarified. In this study, PRF is applied to the afferent axons of the sciatic nerves of rats. A standard radiofrequency (RF) electrode and RF generator is used to apply the RF signal output to the sciatic nerve using standard PRF parameters that have been successfully used in clinical practice. The ultrastructure of the treated axons is observed after 10 days by electron microscopy. A control, sham application is simultaneously applied to the contralateral sciatic nerve to provide a statistical differential comparison. It is found that the internal ultrastructural components of the axons show microscopic damage after PRF exposure, including: abnormal membranes and morphology of mitochondria, and disruption and disorganization of microfilaments and microtubules. The damage appears to be more pronounced for C-fibers than for A-delta and A-beta fibers. The results are discussed in terms of internal electric field strengths and thermodynamic parameters.
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              mRNA expression of cytokines and chemokines in herniated lumbar intervertebral discs.

              The mRNA expressions of cytokines and chemokines were assessed in herniated lumbar disc specimens. To investigate whether the mRNAs of interleukin (IL)-1alpha, tumor necrosis factor (TNF)-alpha, RANTES, IL-8, IL-10, and transforming growth factor (TGF)-beta are expressed in surgically obtained herniated disc specimens; and to discover which of them are the predominant cytokines associated with the clinical symptoms and signs, and whether any differences in the mRNA expression exist depending on the different types of disc herniations. It has been postulated that cytokines are involved in causing radicular leg pain in lumbar disc herniations. Although a few studies have been done on lumbar disc herniations concerning IL-1alpha and TNF-alpha, almost none has been carried out in the cases of the other of cytokines and chemokines. Using a reverse transcription-polymerase chain reaction, mRNA expressions of cytokines and chemokines were investigated in herniated disc specimens. The straight leg raising test, development of radicular pain by back extension, symptom duration, pain intensity using a visual analogue scale, and herniation types were described. The mRNAs of IL-8, TNF-alpha, IL-1alpha, RANTES, and IL-10 were expressed in 16 (70%), 15 (65%), 9 (39%), 4 (17%), and 2 (9%) of the 23 herniated disc specimens, respectively. The mRNA of TGF-beta was expressed in 5 of 10 specimens (50%). IL-8 mRNA expression was associated with the development of radicular pain by back extension and short symptom duration (average 3.8 weeks). The mRNAs of IL-1alpha were expressed more frequently in transligamentous extensions than in subligamentous extensions, but the expression was weak. Interleukin-8 appears to be associated with development of radicular pain by back extension and to be activated on acute or subacute disc herniations. IL-8 seems to participate in the pathomechanism of nerve root inflammation in lumbar disc herniations, which implies that it may be considered a target for therapeutic intervention.

                Author and article information

                Medicine (Baltimore)
                Medicine (Baltimore)
                Wolters Kluwer Health
                April 2017
                14 April 2017
                : 96
                : 15
                Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University, Daegu, Republic of Korea.
                Author notes
                []Correspondence: Min Cheol Chang, Department of Physical Medicine and Rehabilitation, College of Medicine, Yeungnam University 317-1, Daemyungdong, Namku, Daegu 705-717, Republic of Korea (e-mail: wheel633@ 123456hanmail.net ).
                MD-D-17-01006 06604
                Copyright © 2017 the Author(s). Published by Wolters Kluwer Health, Inc.

                This is an open access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. http://creativecommons.org/licenses/by-nc-nd/4.0

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